1. Field of the Invention
The invention relates generally to a method and apparatus for monitoring receivers, and more particularly to methods and apparatus for determining the particular transmitting station from which program signals are received and translated by a monitored receiver and including automobile and portable receivers.
2. Description of the Prior Art
Various arrangements have been employed to determine the channel to which a radio and/or television receiver is tuned. Examples of receiver monitoring methods and apparatus for monitoring receivers are provided by U.S. Pat. Nos. 2,833,859; 3,973,206; 4,048,562, 4,425,578; 4,723,302; 4,764,808; 4,876,736; 4,930,011; 4,943,963; and 4,972,503. While these systems provide improvements over other known arrangements, a need exists for an economically effective system having flexibility to accommodate monitoring a large number of receivers including mobile receivers in a prompt and efficient manner.